RD8200 locators are capable of locating cable to ground faults caused by damaged cable sheaths and can also be used to locate damage to insulation on pipelines. This process is known as Fault-Finding and uses specific fault find signals applied to the target.

Fault find signals can only be applied using Direct Connection method.

The A-frame accessory is used to locate cable sheath faults on power and telecom cables or insulation faults on pipelines.

To use Fault-Find you will need the following equipment:

• RD8200 locator
• Tx-5 or Tx-10 transmitter
• Accessory A-frame with connecting lead
• Direct connection lead and earth stake

There are 2 types of signals that can be used for fault finding:

• 8K Fault Find – useful for sheath faults on cables but can also be used on pipelines over shorter distances.
• CD Fault Find (only available on Tx-10) – this low frequency signal is very useful on pipelines and particularly useful on long distance pipelines. CD can also be used for locating sheath faults on cables.

Preparation

Using RD8200 standard locating techniques locate the cable or pipe for a short distance and trace and mark its route. Remove all earth bonds from the line to be traced during the fault-finding survey. If there are any earth bonds along the path the fault find signal may direct the user to this location as this will be the preferred path for the fault find signal to leak away into the ground and may result in the fault not being located.

Connecting the transmitter

1. With the transmitter switched off connect the Direct Connection lead into the transmitter accessory socket.
2. Clip the red connection lead to the cable, cable sheath or pipe ensuring that the area around the connection is clean and that a positive connection is achieved.
3. Extend the black connection lead as far away as possible at 90° to the probable route of the target cable and clip the connector to the ground stake ensuring that a positive connection is achieved.

NOTE: Always connect the black connection lead to a ground stake and not a water pipe or buried cable, as these may carry the signal.

Reference readings

It is good practice to obtain a reference reading from the ground stake before you attempt to locate a fault on a target line. Reference readings help to provide the following information:

• Severity of fault
• Survey interval

Before taking the reference reading set up the transmitter and locator as follow:

On the transmitter:

1. Select a fault-finding frequency using the key.
2. Use the or  keys to increase or decrease the output signal level.
3. If required you can use the BOOST setting if the fault is located on a high resistance cable or if the cable is long.

WARNING! By selecting 8KFF the transmitter will have the ability to output high voltages and a high voltage warning icon will appear on the transmitter’s LCD.

On the locator:

1. Connect one end of the connection lead to the A-frame socket.
2. Connect the other end to the locator accessory socket.
3. The locator will automatically recognize the A-frame and display the A-frame icon on the LCD.
4. Select a fault-finding frequency using the key.

NOTE: If the locator and transmitter are iLOC enabled then you can remotely control the transmitter using the locator. 

Obtaining a reference reading:

Position the locator approximately 2m (6 feet) from the ground stake and push the A-frame spikes into the ground with the green spike towards the ground stake.

Attach the locator to the A-frame by the retention hook. (If you are holding the locator separately, make sure that the locator is in line with the A-frame and is pointing towards the green spike.) The fault direction arrow should be pointing away from the ground stake. If it is not, make sure that the transmitter is connected correctly (red connector to the cable and black to the ground stake).

Take the dB reading and keep it for reference. If there is a single fault on the cable, it will be approximately the same dB value as the reference reading.

NOTE: To establish how often to take readings on the cable or pipe, move away from the ground stake and take further readings until the arrow has difficulty in locking and the dB reading is low. Measure the distance that the locator is now away from the ground stake. This is the distance that you can safely use between taking readings on the cable or pipe to ensure that you do not miss the fault.